/Engine/Plugins/Runtime/GameplayAbilities/Source/GameplayAbilities/Public/AbilitySystemTestAttributeSet.h
Called just before modifying the value of an attribute. AttributeSet can make additional modifications here. Return true to continue, or false to throw out the modification. Note this is only called during an 'execute'. E.g., a modification to the 'base value' of an attribute. It is not called during an application of a GameplayEffect, such as a 5 ssecond +10 movement speed buff.
virtual bool PreGameplayEffectExecute ( struct [FGameplayEffectModCallbackData](API\Plugins\GameplayAbilities\FGameplayEffectModCallbackData) & Data )